One performance index that is very important in liquid crystal displays is luminance, and the most important factor in determining the luminance is aperture ratio, which refers to the ratio held by an effective transmission region of one pixel in the whole area of the entire pixel.
Currently, the resolution of cell phone products is getting higher and higher, the pixel pitch is getting smaller and smaller, and the aperture ratio of twisted nematic (TN) mode products becomes a bottleneck. Regarding the TN mode products, in order to prevent generation of flicker, the amount of a storage capacitance Cst must be ensured, and thus aperture ratio is restricted greatly. For dual-gate liquid crystal panels, the aperture ratio is lower.
FIG. 1 is a schematic view showing a pixel structure of a conventional liquid crystal panel of a TN mode, in which, between a pixel electrode 7 and a common voltage line 8 (Vcom), there are two insulating layers, i.e. an insulating layer 5 (PVX) and a gate insulating layer 6 (GI). In order to guarantee the storage capacitance Cst, there must be a larger facing area, and area of the common voltage line 8 (Vcom) needs to be made larger. However, after the area of the common voltage line 8 (Vcom) is increased, the aperture ratio will be degraded.